Study on the DQPSK Demodulation Method based on Virtual Radio

摘要

Discrete short time Fourier transformation (DSTFT) is a common and effective method in digital signal processing and analysis. In the most applications, amplitude information of Fourier transform is utilized instead of phase information. An algorithm based on the sliding DSTFT is presented in this paper. The demodulation of DQPSK signal is achieved using phase information in frequency domain. The principle and process of the algorithm are detail researched. The fast recursive algorithm is given under the two window functions, and the bit error rate (BKR) is analyzed. The simulation shows that the DSTFT-based algorithm can get high performance, and facilitate software real-time processing. In the Gaussian white noise channel, when BLR is 10"4, the performance of the algorithm is nearly ldB better than the traditional differential detection method.